226
FXUS62 KCHS 171133
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
633 AM EST FRI JAN 17 2025
SYNOPSIS
HIGH PRESSURE WILL PREVAIL THROUGH THE REST OF THE WEEK. AN
AREA OF LOW PRESSURE AND ASSOCIATED COLD FRONT WILL IMPACT THE
REGION THIS WEEKEND. ANOTHER LOW PRESSURE SYSTEM COULD IMPACT
THE REGION EARLY TO MID NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
THE CENTER OF SFC HIGH PRESSURE WILL SLIDE ACROSS THE FORECAST AREA
TODAY, MOVING OVER THE ADJACENT ATLANTIC WATERS THIS AFTERNOON.
UNRESTRICTED INSOLATION SHOULD SUPPORT TEMPERATURES PEAKING IN THE
UPPER 50S ACROSS THE SC LOWCOUNTRY TO LOW 60S ACROSS SE GA. AS
TEMPERATURES WARM TO AROUND 60 DEGREES, HIGH RESOLUTION GUIDANCE
INDICATES THAT A SEA BREEZE FEATURES WILL ADVANCE INLAND LATE THIS
AFTERNOON. THIS BOUNDARY SHOULD SHIFT WINDS FROM THE SOUTH AND SFC
DEWPOINTS WILL GRADUALLY WARM.
NEAR TERM GUIDANCE INDICATES THAT A H5 SHORTWAVE WILL RAPIDLY TRACK
FROM THE GREAT PLAINS TO THE LOWER MISSISSIPPI RIVER VALLEY TONIGHT.
AT THE SFC, BROAD LOW PRESSURE IS EXPECTED TO GRADUALLY ORGANIZE
ACROSS THE DEEP SOUTH. AS THE LOW TRACKS EAST, PW VALUES ACROSS THE
FORECAST WILL STEADILY INCREASE THROUGH THE NIGHT, REACHING AROUND 1
INCH BY DAYBREAK SATURDAY. CONDITIONS SHOULD REMAIN DRY DURING THE
EVENING. IN FACT, IT APPEARS THAT THE COOLEST TEMPERATURES WILL
OCCUR DURING THE EVENING, THEN GRADUALLY WARM THROUGH THE REST OF
THE NIGHT AS CLOUD COVER THICKENS. LOW TEMPERATURES WILL GENERALLY
RANGE AROUND 40 DEGREES, WITH MID 40S ALONG THE COAST. ISOLATED TO
SCATTERED SHOWERS ARE FORECAST TO DEVELOP ACROSS THE FORECAST HOURS
DURING THE PRE-DAWN HOURS SATURDAY MORNING.
SHORT TERM /SATURDAY THROUGH MONDAY/
AS A DEEP UPPER-LEVEL TROUGH CENTERED OVER THE MIDDLE PORTION OF
CANADA DIGS IN FROM THE NORTHWEST, AN ASSOCIATED ARCTIC FRONT WILL
BEGIN TO APPROACH THE REGION FROM THE WEST. ALONG WITH THIS, A
RATHER MOIST AIRMASS WILL BE USHERED INTO THE REGION IN SATURDAY
MORNING WITH PWATS >1". THIS WILL ALLOW FOR A RAINY SATURDAY MORNING
AND AFTERNOON WITH MOST AREAS RECEIVING AROUND 0.50 TO 1.25 INCHES.
POPS ARE ABOVE 80% FOR MOST OF THE MORNING AND THEN START TO SLOWLY
DIMINISH HEADING INTO SATURDAY NIGHT AND SUNDAY MORNING AS THE FRONT
PUSHES THROUGH SUNDAY AFTERNOON. HIGHS WILL REACH INTO THE UPPER
50S/LOWER 60S ON SATURDAY AND SUNDAY. LOWS ON SATURDAY NIGHT DROP
INTO THE UPPER 40S TO LOW 50S, HOWEVER SUNDAY NIGHT LOWS DROP INTO
THE MID 20S TO LOW 30S WITH WIND CHILLS 15 TO 20 DEGREES. THIS IS
WELL WITHIN COLD WEATHER ADVISORY CRITERIA (11 TO 20 DEGREES) AND
WILL LIKELY BE ISSUED FOR SUNDAY NIGHT. HEADING INTO MONDAY, STRONG
CAA DOMINATES AND CONDITIONS WILL BECOME BREEZY. HIGHS WILL ONLY
REACH INTO THE MID 40S.
LONG TERM /MONDAY NIGHT THROUGH THURSDAY/
MONDAY NIGHT: WITH STRONG CAA IN PLACE, LOWS WILL DROP INTO THE LOW
TO MID 20S INLAND AND UPPER 20S TO LOW 30S ALONG THE BEACHES. SOME
WIND CHILL VALUES INLAND REACH DOWN TO 15 TO 20 DEGREES AND AGAIN
THIS IS WELL WITHIN COLD WEATHER ADVISORY CRITERIA AND WILL LIKELY
BE ISSUED FOR MONDAY NIGHT.
TRANSITIONING TO TUESDAY AND BEYOND, THE FORECAST BECOMES
INCREASINGLY TRICKY AND POTENTIALLY IMPACTFUL. MUCH OF THE FORECAST
DEPENDS ON HOW FAR SOUTH AND OFFSHORE THE LOW PRESSURE TRACKS OFF
THE SOUTHEAST U.S. COASTLINE. WITH THE 00Z GFS/ECMWF/CMC
DETERMINISTIC MODEL RUNS SUGGEST SNOW WILL BE THE MAIN P-TYPE WITH
THIS SYSTEM. POPS WERE INCREASED A BIT FOR TUESDAY AND WEDNESDAY
MORNING TO 40-60%. MOST OF THE MODELS ARE IN AGREEMENT THAT MOST OF
THE PRECIPITATION SHOULD END BY WEDNESDAY AFTERNOON. HOWEVER, SOME
UNCERTAINTY STILL REMAINS REGARDING THE AMOUNT OF SNOWFALL WE MIGHT
RECEIVE. THE COLD TEMPERATURES IS AN ASPECT THAT WE CAN SPEAK ABOUT
WITH HIGH CONFIDENCE, AND IT WILL BE VERY COLD. IN FACT, THERE ARE
SIGNALS THAT SOME LOCATIONS COULD SEE WIND CHILLS DROP BELOW 10
DEGREES ON TUESDAY NIGHT AND WEDNESDAY NIGHT WHICH IS DIPPING INTO
EXTREME COLD WARNING TERRITORY (10 DEGREES OR COLDER). WE COULD EVEN
BREAK THE RECORD LOW TEMPERATURES AT KCHS/KCXM/KSAV ON THURSDAY.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
VFR CONDITIONS WILL PREVAIL AT KCHS, KJZI, AND KSAV THROUGH 12Z
SATURDAY. LIGHT RAIN SHOWERS SHOULD DEVELOP OVER THE TERMINALS
DURING THE HOURS SATURDAY MORNING.
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS ARE LIKELY SATURDAY
AS WIDESPREAD RAINS MOVE THROUGH IN ASSOCIATION WITH A COLD FRONT.
THE RISK FOR RESTRICTIONS IN LOW VSBYS AND CEILINGS WILL RETURN
TUESDAY MORNING INTO WEDNESDAY NIGHT AS A POTENTIAL WINTER STORM
IMPACTS THE REGION. THERE IS A CHANCE FOR FREEZING OR FROZEN
PRECIPITATION IMPACTING ALL TERMINALS DURING THIS TIME PERIOD.
MARINE
HIGH PRESSURE WILL BUILD OVER THE MARINE ZONES THIS AFTERNOON, THEN
WILL GRADUALLY WEAKEN TONIGHT. THIS PATTERN WILL YIELD CHANGING WIND
DIRECTIONS, SPEEDS SHOULD REMAIN BETWEEN 5 TO 10 KTS. WAVE HEIGHTS
ARE FORECAST TO REMAIN BETWEEN 1 TO 2 FT.
SATURDAY THROUGH WEDNESDAY: SOUTHERLY/SOUTHWESTERLY WINDS BEGIN TO
INCREASE AHEAD OF THE APPROACHING COLD FRONT TO 10 TO 15 KT ON
SATURDAY. BEHIND THE COLD FRONT, WINDS BECOME NORTHWESTERLY AND PICK
UP TO 20 TO 25 KT WITH GUSTS UP TO 30 KT. SMALL CRAFT ADVISORIES
APPEAR LIKELY FOR SUNDAY NIGHT THROUGH MONDAY MORNING. SEAS WILL
PEAK 3-5 FT OVER THE NEARSHORE WATERS OUT 20 NM AND 4-6 FT OVER THE
GEORGIA OFFSHORE WATERS OUT 20-60 NM. ANOTHER SURGE WILL OCCUR
MONDAY NIGHT INTO TUESDAY AS THE PRESSURE GRADIENT TIGHTENS BETWEEN
INLAND HIGH PRESSURE AND A DEVELOPING LOW OFFSHORE. NORTH TO
NORTHEAST WINDS 20-25 KT WITH GUSTS TO 30 KT WILL OCCUR DURING THIS
TIME WITH SEAS 2-4 FT WITHIN 20 NM AND 5-8 FT OVER THE GEORGIA
OFFSHORE WATERS OUT 20-60 NM. SMALL CRAFT ADVISORIES APPEAR LIKELY
AGAIN FOR MONDAY NIGHT THROUGH WEDNESDAY AFTERNOON FOR ALL MARINE
ZONES EXCEPT FOR THE OUTER GEORGIA WATERS WHICH WILL PROBABLY NEED A
GALE WARNING. SOME WINTER PRECIPITATION COULD FALL OVER THE COASTAL
WATERS MONDAY NIGHT INTO TUESDAY.
CLIMATE
RECORD LOW TEMPERATURES:
THURSDAY, JANUARY 23:
KCHS: 19/1985
KCXM: 24/2003
KSAV: 19/1960
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
NEAR TERM...NED
SHORT TERM...DENNIS
LONG TERM...DENNIS
AVIATION...DENNIS/NED
MARINE...DENNIS/NED
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page